Children in elementary school are in the Concrete Operations Stage of Piaget's Stages of Cognitive Development. They are able to grasp certain abstract concepts; however, they have not moved away from the need to use concrete objects in learning. One of the best ways to teach this age group, therefore, is with manipulatives. These tools overflow the shelves of teacher stores. Learning to tell time should involve a play clock with moving hands. Lessons about addition should begin with actual objects such as cubes, beads or counting bears. Physically allowing children to count out three cubes and add two more cubes to the group shows them concretely that 3 + 2 = 5. Even older students in elementary school, though on the cusp of moving out of the concrete stage of development, benefit from hands-on lessons. Copious manipulatives exist for lessons on fractions, geometric shapes and even basic algebra skills.
Students in elementary school have shorter attention spans than their older counterparts. Therefore, the best way to teach them math skills is through short lessons, repetition and review. Teaching a skill for 15 minutes a day for three days, assigning practice for 15 minutes on the fourth day, assigning an equally short homework assignment, and then testing them the fifth day on that skill will likely yield better results than doing an hour-long lesson with this age group. Keeping things brief but frequent is the best approach for math in elementary school. Students in upper elementary grades, say third through fifth, may be ready for a longer lesson (maybe 30 minutes), but in general, elementary students cannot focus on a math lesson for as long as a high-schooler (who may have one or even two hours of math in a day, depending on the format of the classes).
Many elementary students know how to use a computer, and if a teacher or parent has access to one, she can use technology to assist in teaching math skills. Educational games on the computer that reinforce the math lessons of the week or review prior skills can be excellent tools for this age group.
Elementary students may seem mature and grown-up at times, but they still respond very well when educators turn learning into a game. Board games can be used to reinforce counting for younger children or even to teach older students about probability. (If the game has a spinner, students can discuss the probability of landing on a certain number or color.) Dividing up a class and then making a math review into a "quiz show" can get students excited and competing to get the most answers correct.